# print('hello world')

# print(1+2-3)
# print(1+2*3)
# print(1+2/3)
#
# print((67.5+89.0+12.9+32.2)/4)

# a=10
# a1=20
#
# 1a=10（起名字错误，数字、字符、下划线且数字不能开头）
# if=10
# a=10
# b=a
# print(b)
#
# a=20
# print(a)

# a=10
# print(type(a))
#
# b = 0.5
# print(type(b))
#
# c="hello"
# print(type(c))
#
# e="My name is 'lijiale'"
# print(type(e))
#
# f="'My' name is 'liuchangsheng'"
# print(type(f))
#
# print(len(c))
#
# a1="hello"
# a2="world"
# print(a1+a2)
#
# c1=True
# c2=False
# print(type(c1))
# print(type(c2))

#
# a=10
# print(f"a={10}")
# print(f"a={a+10}")